Mammalian skin acts as the interface with the environment, serving both as the primary barrier to chemical and microbiological intrusion from the outside, as well as the body's container. The most interesting and important element of the barrier is the thin, outermost layer referred to as the stratum corneum (SC). This layer is a lipid protein mosaic of fully differentiated cells which serves (a) as the barrier to chemical and biological exposure, (b) to regulate water loss and retain solutes within the body, and (c) as a potential route of local and systemic administration of drugs. Finally, the SC is the site of the lesion in a number of diseases which are characterized by abnormal water loss rates and other barrier aberrations. In addition, the subadjacent epidermal tissue can serve as a physical, metabolic and immunologic barrier to certain drugs and pathogens. Thus, the barrier function of mammalian skin is the research focus for a wide variety of disciplines including membrane biophysics, cell biology, immunology, toxicology, clinical dermatology and drug delivery. Due to this breadth of interest in the SC and the relatively new nature of research in this field, there exisits no single forum for the exchange of ideas among these disparate disciplines. The Gordon Research Conference on Barrier Function of Mammalian Skin is therefore, both a timely and appropriate forum for this rapidly developing field.